Disc brake friction pad and retention system

Abstract: An improved friction pad (8) which may be incorporated in a vehicle disc brake including a rotor (14) having oppositely disposed friction surfaces, a caliper (28) having recesses (30) defined in portions disposed proximate the friction surfaces of the rotor (14). Each friction pad (8) consists of a backing plate (10) and friction material (12) secured to a major portion of the backing plate (10). Each backing plate (10) includes a pair of circumferentially displaced radially extending projections (16) which receive a single-piece clip (18) having a pair of apertures (20) defined by upturned portions (22,24) which register with the projections (16) providing a resilient interfitting structural connection. The single-piece clip (18) includes a central portion (26) which may be elastically deformed radially inwardly to provide a radially directed resilience to the respective assembly. When the friction pads (8) are installed in the caliper recesses (30), the central portions (26) of the single piece clip (18) protrude radially such that a bridge (32) installed and rotated into place across the caliper (28) achieves displacement of the central structural portions (26) providing a retention mechanism imparting a radially inwardly directed resilience.

Description: BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a disc brake comprising a retention system for a friction pad. DESCRIPTION OF THE RELATED ART The present invention is particularly applicable to a disc brake assembly of the type which includes a rotor mounted for rotation with a vehicle wheel and a caliper straddling the periphery of the rotor. Friction pads are carried by the caliper on opposite sides of the rotor and are movable into contact with oppositely disposed friction surfaces of the rotor by actuating means driven by an air actuator. In a caliper disc brake, each friction pad is located intermediate one leg of the caliper and the adjacent friction surface of the rotor. The actuating mechanism is usually carried by one leg of the caliper and serves to move the friction pad adjacent to that leg axially into contact with the rotor. The reaction force of such contact serving to draw the other leg of the caliper and the corresponding other friction pad into contact with the opposite surface of the rotor. Although various arrangements are known for supporting friction pads within a disc brake assembly, some require additional elements for preventing inadvertent displacement of the friction pads away from their operative position and others require disassembly of parts or retraction of the actuating mechanism to replace the friction pads which may not be easily accomplished. Others relying on radially converging edges or angularly disposed surfaces to support the friction pad or to transmit torque to the supporting caliper require careful attention to tolerances during manufacture to assure proper fit and location of cooperating parts when the brake is assembled. From document WO-A-92/00465 a disc brake comprising a retention system for a friction pad is known which comprises a backing plate including radially extending projections, a retention member having apertures positionally registering with the projections, the outer ends of the retention member providing a resilient force directed against opposing sides of the radially extending projections maintaining the retention member secured to the backing plate, and a bridge maintained in contact with the retention member. A similar disc brake system is shown in EP-A-0 248 385. SUMMARY OF THE INVENTION It is an object of the present invention to provide a disc brake assembly in which the friction pads are readily accessible for inspection or replacement purposes. This object is attained by a disc brake according to claim 1. The disc brake according to the present invention has an improved friction pad and a caliper assembly having recesses defined in portions disposed proximate the friction surfaces of the rotor. Each friction pad consists of a backing plate and friction material secured to a major portion of the backing plate. Each backing plate includes a pair of circumferentially displaced radially extending projections which receive a single-piece clip having a pair of apertures defined by upturned portions which register with the projections providing a resilient interfitting structural connection. The single-piece clip includes a central portion which may be elastically deformed radially inwardly to provide a radially directed resilience to the respective assembly. When the friction pads are installed in the caliper recesses, the central portions of the single piece clip protrude radially such that a bridge installed and rotated into place across the caliper achieves displacement of the central structural portions providing a retention mechanism imparting a radially inwardly directed resilience. These and other aspects of the present invention will become more readily apparent by reference to the following detailed description of the embodiments as shown in the drawings. DESCRIPTION OF THE DRAWINGS Figure 1 is a cross sectional view of a disc brake assembly including a disc brake fraction pad having the single-piece clip of the present invention installed thereon; Figure 2 is a plan view of the single-piece clip; Figure 3 is a cross section of the disc brake assembly taken along lines 3-3 of Figure 1; Figure 3A is a cross sectional view taken along lines 3A-3A of Figure 3; Figure 4 is a plan view of a disc brake assembly of the present invention; Figure 5 is a cross section of the backing plate and single-piece clip prior to installation; and Figure 6 is a plan view of a disc brake friction pad of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment of the present invention as illustrated in Figure 1 features a backing plate 10 having a friction material 12 secured thereto. Rotor 14 is shown for reference. Circumfrentially spaced radial projections 16,16 on backing plate 10 provide structure for securance of single-piece clip 18. Single-piece clip 18 is symmetrical about a central point and includes apertures 20,20 located at opposing ends and defined by upturned portions 22,24. A resilient engagement of upturned portions 22,24 against opposing side walls of radial projections 16,16 define a structural securance maintaining contact with backing plate 10. Central portion 26 is elastically deformable over a limited range and thereby capable of providing a resilience in response to such deformation. Disc brake pad 8 may be installed within saddle 29 resting in recess 30 which provides a circumfrential and radial positional definition for brake pad 8. When disc brake pad 8 is installed in recess 30 of saddle 29, bridge 32 as shown in Figure 3 and 4 may be installed thereacross in radiused slots 34,34 defined in opposing sides of caliper 28. The radial dimension of recess 30 provides sufficient radial protrusion of portion 26 of single-piece clip 18 to facilitate partial displacement of portion 26 upon the installation of bridge 32 thereby defining a system resilience that provides an anti-rattle function. Pins 36,36 may be installed in caliper 28 to retain bridge 32 in place resistant to accelerations which may be encountered in vehicle performance. During installation, bridge 32 may be installed in radiused slots 34,34 by first inserting one end of bridge 32 in the respective radiused slot and rotating bridge 32 thereabouts thus driving bridge 32 into a position in which portion 26 is compressed. To remove brake pads 8,8, upon the necessity of maintenance procedures, the process may be reversed. First pins 36,36 are removed and bridge 32 may be rotated from caliper 28 thereby exposing disc brake pads 8,8 at which point disc brake pads 8,8 may be radially extracted from caliper 28. Circumfrentially extending opposed projections 17,17offer an engagement structure suitable for receiving a flat bladed screwdriver which may be wedged against caliper 28 to facilitate radial extraction of pads 8,8.

Claims: A disc brake comprising a retention system for a friction pad, the disc brake comprising: a backing plate (10) defined by a rectangularly shaped member including circumferentially spaced radially extending projections (16); a retention member (18) having apertures (20) positionally registering with the projections (16); a caliper assembly including a rotor (14) having opposing friction surfaces and being rotatable; a bridge (32) maintained in contact with the retention member (18); the rotor (14) having opposed caliper portions (28), each caliper portion (28) defining a recess (30) disposed for receiving a disc brake pad (8); the apertures (20) being defined by upturned lips (22, 24) formed at opposite ends; the upturned lips (22, 24) providing a resilient force directed against opposing sides of the circumferentially spaced radially extending projections (16) maintaining the member (18) secured to the backing plate (10); the opposed caliper portions (28) having slots (34) formed in an outermost radial portion thereof; said bridge (32) being disposed in the slots (34); and the slots (34) being radiused and the bridge (32) being rotatably installed in the slots (34) of the caliper portions. The disc brake of claim 1, wherein the member (18) includes an elastically deformable portion (26) which defines a radially directed resilience in reaction to displacement in such direction. The disc brake of claim 1 or 2, wherein the bridge (32) is retained in the slots (34) by axially extending cylindrical members (36) disposed in openings defined in opposing ends of the slots (34). The disc brake of any one of the preceding claims, wherein the retention member (18) includes an elastically deformable portion (26) which is elastically deformed by the bridge (32) after installation of the disc brake pads. The disc brake of any one of the preceding claims, wherein to each recess (30) a pair of lips (22, 24) is assigned which lips (22, 24) are arranged on opposite sides of the corresponding projection (16).

Inventors: FORNI ROBERTO, HARRUP CLIVE, SACCHI GIOVANNI, FORNI, ROBERTO, HARRUP, CLIVE, SACCHI, GIOVANNI
Applicants: MERITOR HEAVY VEHICLE TECH, MERITOR HEAVY VEHICLE TECHNOLOGY LLC
Application year: 1994
Main classification: F16D65
IPC codes: F16D65